n to be specially adapted to secure such dispersal by the agency of
birds and mammals; while the same end is secured in other cases by
downy seeds to be wafted through the air, or by hooked or sticky
seed-vessels to be carried away, attached to skin, wool, or feathers.

Here, then, we have an enormous extension of the region of utility in
the vegetable kingdom, and one, moreover, which includes almost all the
specific characters of plants. For the species of plants are usually
characterised either by differences in the form, size, and colour of the
flowers, or of the fruits; or, by peculiarities in the shape, size,
dentation, or arrangement of the leaves; or by peculiarities in the
spines, hairs, or down with which various parts of the plant are
clothed. In the case of plants it must certainly be admitted that
"specific" characters are pre-eminently adaptive; and though there may
be some which are not so, yet all those referred to by Darwin as having
been adduced by various botanists as useless, either pertain to genera
or higher groups, or are found in some plants of a species only--that
is, are individual variations not specific characters.

In the case of animals, the most recent wide extension of the sphere of
utility has been in the matter of their colours and markings. It was of
course always known that certain creatures gained protection by their
resemblance to their normal surroundings, as in the case of white arctic
animals, the yellow or brown tints of those living in deserts, and the
green hues of many birds and insects surrounded by tropical vegetation.
But of late years these cases have been greatly increased both in number
and variety, especially in regard to those which closely imitate special
objects among which they live; and there are other kinds of coloration
which long appeared to have no use. Large numbers of animals, more
especially insects, are gaudily coloured, either with vivid hues or with
striking patterns, so as to be very easily seen. Now it has been found,
that in almost all these cases the creatures possess some special
quality which prevents their being attacked by the enemies of their kind
whenever the peculiarity is known; and the brilliant or conspicuous
colours or markings serve as a warning or signal flag against attack.
Large numbers of insects thus coloured are nauseous and inedible;
others, like wasps and bees, have stings; others are too hard to be
eaten by small birds; while sna